What are function of radio waves?

To transmit. (I couldn't help it. Really.)

A great number of electronic circuits need to send information to a distant place. "Distant" isn't really a hard-and-fast term; it could be an inch away over a piece of hook-up wire, to the next room via your Wi-fi connection, to the next town over FM radio waves, a country on the other side of the ocean via a submarine cable, or to another planet with a dish pumping out megawatts of microwave energy. The system that structures the information in such a way that it can be sent and increases its amplitude to ensure it will get where you need it to go, is the transmitter.